Sirocco fan, blowing device, and air conditioner

ABSTRACT

A boss of an impeller and a rotation shaft are fastened together without partially notching or removing a blade of the impeller. A sirocco fan includes an impeller including a boss formed to protrude outward from and end face sucking air when the impeller rotates. The boss is provided with a screw hole opening, on a side face of a protruding portion of the boss, for fastening the rotation shaft with a screw.

TECHNICAL FIELD

The present invention relates to a sirocco fan and an air conditionerincluding the sirocco fan as a blowing device.

TECHNICAL FIELD

A conventional indoor unit for an air conditioner includes inside: anair blower; and a heat exchanger surrounding an upper portion and afront portion of the air blower, as disclosed, for example, in PatentDocument 1. In such an indoor unit, the air blower rotates to suck airfrom an inlet in an upper portion of the indoor unit. The sucked airpasses through the heat exchanger, and then blows out from an outlet ina front-lower portion of the indoor unit.

An air conditioner recently developed is capable of purifying air inaddition to conditioning air. For example, a high efficiency particulateair filter (HEPA filter) has a large air-flow resistance. Hence, the useof the HEPA filter for air purification inevitably reduces a volume ofair blowing from the outlet. When the HEPA filter is used for airpurification, it is necessary to secure a sufficient volume of the air(a sufficient volume of the air to be sucked).

A typical air conditioner includes a cross-flow fan as a blowing device.In order to obtain a sufficient volume of air, use of a sirocco fan ispreferable. As illustrated in FIG. 8, for example, multiple sirocco fans113 (two in FIG. 8) each including two impellers 113 a and 113 b areconnected in series to be used as a blowing device.

To rotate the sirocco fan 113, the two impellers 113 a and 113 b need tobe mounted on a rotation shaft 132 which transmits rotational force of anot-shown motor. In mounting the rotation shaft 132, for example, therotation shaft 132 is passed through a boss 131 formed inside theimpeller 113 a, and is fastened with a screw inserted into a screw hole131 a opened on the boss 131.

CITATION LIST Patent Literature

[Patent Document 1] Japanese Unexamined Patent Application PublicationNo. 2005-147508 (published on Jun. 9, 2005).

SUMMARY OF INVENTION Technical Problem

As illustrated in FIG. 8, for example, the conventional sirocco fan hasthe boss 131 formed inside the impeller 113. Hence, the screw hole 131 afor fastening the rotation shaft 132 is also formed inside the boss 131.Hence, when the screw is inserted in the screw hole 131 a on the boss131, a notch 113 a has to be provided to a portion of a blade of theimpeller 113 a. Alternatively, the blade of the impeller 113 a has to bepartially removed for the screw to pass through the removed portion.Accordingly, when the blade of the impeller 113 a is partially notchedor removed, the impeller 113 a fails to obtain a sufficient volume ofair.

An aspect of the present invention intends to provide a sirocco fan inwhich a boss of an impeller and a rotation shaft can be fastenedtogether without partially notching or removing a blade of the impeller.

Solution to Problem

In order to solve the above problem, a sirocco fan according to anaspect of the present invention includes: an impeller including a bossfor securing a rotation shaft transmitting rotational force of a motor,the impeller being configured to rotate to suck air from a direction inparallel with the rotation shaft, and to eject the air from a rotationface of the impeller, wherein the boss is formed to protrude outwardfrom an end face of the impeller sucking the air, and is provided with ascrew hole opening, on a side face of a protruding portion of the boss,for fastening the rotation shaft with a screw.

Advantageous Effects of Invention

An aspect of the present invention makes it possible to fasten a boss ofan impeller and a rotation shaft together without partially notching orremoving a blade of the impeller.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating an appearance of an indoorunit for an air conditioner according to an embodiment of the presentinvention.

FIG. 2 is a vertical cross-sectional view of the indoor unit illustratedin FIG. 1.

FIG. 3 (a) is a schematic side view of the indoor unit, illustratingconditions of an open-close lid and an air guiding plate when the airconditioner of the embodiment is OFF. FIG. 3 (b) is a schematic sideview of the indoor unit, illustrating conditions of the open-close lidand the air guiding plate when the air conditioner is in anair-conditioning mode and set cooling. FIG. 3 (c) is a schematic sideview of the indoor unit, illustrating conditions of the open-close lidand the air guiding plate when the air conditioner is in an airpurification mode and set cooling.

FIG. 4 is a perspective view schematically illustrating a configurationof a blowing device according to this embodiment.

FIG. 5 is a view illustrating how to connect together a sirocco fan andmotor included in the blowing device illustrated in FIG. 4.

FIG. 6 is a schematic view illustrating a configuration of a blowingdevice according to a second embodiment of the present invention.

FIG. 7 is a schematic view illustrating a configuration of a blowingdevice according to a third embodiment of the present invention.

FIG. 8 is a schematic view illustrating a configuration of aconventional sirocco fan.

DESCRIPTION OF EMBODIMENTS First Embodiment

Described below are embodiments of the present invention, with referenceto the drawings. FIG. 1 is a perspective view illustrating an appearanceof an indoor unit 1 for an air conditioner according to this embodiment.FIG. 2 is a vertical cross-sectional view of the indoor unit 1 for theair conditioner illustrated in FIG. 1.

(Outline of Indoor Unit 1)

As illustrated in FIG. 1, the indoor unit 1 of the air conditionerincludes an air guiding plate 3 in front of an indoor-unit body 2. Asillustrated in FIG. 2, the indoor-unit body 2 includes: a first inlet 11in an upper portion thereof; a second inlet 12 in a lower portionthereof; an air-blowing fan 13 and a heat exchanger 14 therein; and anoutlet 17 in a front portion thereof. The air-blowing fan 13 and theheat exchanger 14 constitute a blowing device.

Moreover, the indoor unit 1 includes: a first filter 15 inside (below)the first inlet 11; and a second filter 16 inside (above) the secondinlet 12. For example, the first filter 15 is functionally equivalent toa prefilter, and lower in performance and smaller in air-flow resistancethan the second filter 16. For example, the second filter 16 is an HEPAfilter, and higher in performance and greater in air-flow resistancethan the first filter 15.

In the indoor unit 1, the air sucked from the first inlet 11 passesthrough the first filter 15, the air-blowing fan 13, and the heatexchanger 14, and blows out from the outlet 17. Furthermore, the airsucked from the second inlet 12 passes through the second filter 16, theair-blowing fan 13, and the heat exchanger 14, and blows out from theoutlet 17.

The first inlet 11 is provided with an open-close lid 18 opening andclosing the first inlet 11. FIG. 3 (a) is a schematic side view of theindoor unit 1, illustrating conditions of the open-close lid 18 and theair guiding plate 3 when the air conditioner is OFF. FIG. 3 (b) is aschematic side view of the indoor unit 1, illustrating conditions of theopen-close lid 18 and the air guiding plate 3 when the air conditioneris in an air-conditioning mode and set cooling. FIG. 3 (c) is aschematic side view of the indoor unit, illustrating conditions of theopen-close lid 18 and the air guiding plate 3 when the air conditioneris in an air purification mode and set cooling.

As illustrated in FIG. 3 (a), the open-close lid 18 is closed when theair conditioner is OFF. Moreover, as illustrated in FIG. 3 (b), theopen-close lid 18 is open when the air conditioner operates,prioritizing air conditioning over air purification (in theair-conditioning mode). Furthermore, as illustrated in FIG. 3 (c), theopen-close lid 18 is closed when the air conditioner operates,prioritizing air purification over air conditioning (in the airpurification mode).

The air-blowing fan is a sirocco fan, and serves as a blowing device ofthe indoor unit 1 for the air conditioner. The blowing device will bedescribed later in detail.

The heat exchanger 14 includes two heat exchangers vertically connectedtogether with the connection of the two heat exchangers protrudingforward (in a dogleg shape), and provided in front of the air-blowingfan 13 (closer to the front of the indoor unit 1 than the air-blowingfan 13 is).

(Structure of Blowing Device)

FIG. 4 is a perspective view schematically illustrating a blowing deviceaccording to this embodiment.

The illustration (a) in FIG. 5 shows a side view of the blowing device.The illustration (b) shows a side cross-sectional view of the blowingdevice in the illustration (a). Note that, for the sake of thedescription, FIG. 5 exemplifies a case where the air-blowing fan 13 isplaced to one side of a driving motor (a motor) 33.

As illustrated in FIG. 4, the blowing device according to thisembodiment includes: a cabinet 30; two air-blowing fans 13; and adriving motor 33. The air-blowing fans 13 and the driving motor 33 arelongitudinally arranged inside the cabinet 30. The driving motor 33 isplaced between the two air-blowing fans 13, and transmits rotationalforce to the both air-blowing fans 13. That is, the driving motor 33here is a dual-shaft motor having rotation shafts 32 longitudinallyaligned.

Each of the rotation shafts 32 for transmitting the rotational forcefrom the driving motor 33 is inserted in a boss 31 for one of theair-blowing fans 13. The rotation shaft 32 is then screwed and fastened.Across the driving motor 33 from the air-blowing fan 13, the rotationshaft 32 is supported by a bearing 34, and inserted in the boss 31 forthe air-blowing fan 13. The rotation shaft 32 is then screwed andfastened.

The air-blowing fan 13 shown in the illustration (b) of FIG. 5 is asirocco fan including two impellers 13 a connected together throughtheir respective disc faces 13 b. That is, in the air-blowing fan 13,each of the impellers 13 a rotates in a predetermined direction to suckair from an end face 13 c, of the impeller 13 a, in parallel with therotation shaft 32, and ejects the air from a rotation face 13 d of theimpeller 13 a.

The boss 31 of the impeller 13 a is a hollow tube made of aluminum. Theboss 31 is formed to penetrate the disc face 13 b of the impeller 13 a,and partially protrudes out of the end face 13 c across from the discface 13 b. That is, the boss 31 is formed to protrude outward from theend face 13 c (the end face across from the disc face 13 b) sucking theair when the impeller 13 a rotates. The boss 31 is provided with a screwhole 31 a opening, on a side face of a portion of the boss 31 partiallyprotruding from the impeller 13 a, for fastening the rotation shaft 32with a screw. The rotation shaft 32 is made of stainless, and transmitsdriving force of the driving motor 33.

Hence, the screw hole 31 a is open on the side face of the boss 31protruding from the impeller 13 a. Such a feature eliminates the need ofa conventional notch to be provided to the impeller 13 a for tighteninga screw, facilitating the tightening with a screwdriver.

As to the position of each screw hole 31 a, as shown in the illustration(b) in FIG. 5, the screw holes 31 a are open, on their respective bosses31 for the horizontally arranged impellers 13 a, to face completelyopposite from each other (i.e., one of the screw holes 31 a faces up andthe other screw hole 31 faces down); that is, the screw holes 31 a shift180° from each other in a rotation direction of the rotation shaft 32.Such a feature makes it possible to attain a weight-distribution balancewhen a screw is tightened in the screw hole 31, contributing to stablerotation of the air-blowing fan 13.

Note that the screw holes 31 a may be open on different positions of thebosses 31 of the two impellers 13 a. The screw holes 31 a do not have toshift 180° from each other in the rotation direction of the rotationshaft 32.

In other words, preferably, the two impellers 13 a may be connectedthrough the disc faces 13 b across from the end faces 13 c sucking air,and the screw hole 31 a opening on the boss 31 of one of the twoimpellers 13 a and the screw hole 31 a opening on the boss 31 of anotherone of the two impellers 13 a may be provided not in a single plane.

Moreover, when the air-blowing fan 13 includes multiple air-blowing fans13, the screw holes 31 opening on the bosses 31 of the impellers 13 amay sequentially shift 90° from each other in the rotation direction ofthe rotation shaft 32.

Furthermore, the screw hole 31 a may be open on the side face of theboss 31 protruding completely outward from the end face 13 c sucking theair when the impeller 13 a rotates. Alternatively, the screw hole 31 amay be open on a side face of the boss 31 slightly inward in relation tothe end face 13 c. At least, the screw hole 31 a may be positioned toallow for an easy access of a screwdriver when the screw is tightened inthe screw hole 31 a.

Advantageous Effects

In the above blowing device, a blade of the impeller 13 a does not haveto be partially notched or removed in order to pass a screw through thescrew hole 31 a, opening on the boss 31, when the boss 31 is fastened tothe rotation shaft 32, unlike the case illustrated in FIG. 8 of theconventional art when the boss 31 is formed inward in relation to theair-sucking end face 13 c of the impeller 13 a.

Such features make it possible to reduce a decrease in a volume of theair when a blade of the impeller 13 a is partially notched or removed.

In addition, a mold for forming the impeller does not have to be shapedinto a complex shape, unlike the case where a blade of the impeller isto be partially notched or removed. Such a mold contributes to reductionin manufacturing costs.

Moreover, as shown in the illustration (b) of FIG. 5, the boss 31 isformed to protrude from the impeller 13 a, and the protruding portionhas the screw hole 31 a. Hence, the rotation shaft 32 does not have topass through the boss 31. Such a feature makes it possible to make theweight of the blowing device lighter, compared with a conventional casewhere the rotation shaft passes through the boss.

Second Embodiment

Described below is still another embodiment of the present invention,with reference to the drawings. Note that, for the sake of explanation,identical reference signs are used to denote components with identicalfunctions between the preceding embodiment and this embodiment. Suchcomponents will not be elaborated upon here.

Exemplified in the first embodiment is a blowing device including adual-shaft motor serving as the driving motor 33. Alternatively,exemplified in this embodiment is a blowing device including asingle-shaft motor serving as the driving motor 33. The single-shaftmotor is provided with the rotation shaft 32 on one side alone.

FIG. 6 is a perspective view schematically illustrating the blowingdevice according to this embodiment.

As illustrated in FIG. 6, the blowing device according to thisembodiment is similar in including the two air-blowing fans 13 and theone driving motor 33 to the blowing device (in FIG. 4) according to thefirst embodiment. The blowing device according to this embodiment isdifferent in placement of the driving motor 33 from the blowing deviceaccording to the first embodiment. The two air-blowing fans 13 areconnected together in series with a joint 35 connecting the bosses 31facing each other. The rotation shaft 32 of the driving motor 33 isconnected to the boss 31, of one of the air-blowing fans 13 (theair-blowing fan 13 on the observer's right in FIG. 6), across from thejoint 35. Thus, the rotational force of the driving motor 33 istransmitted to the boss 31 connected to the rotation shaft 32 of thedriving motor 33, and to the other boss 31 of the air-blowing fan 13 onthe left connected through the joint 35 to the air-blowing fan 13 on theright provided with the boss 31. Hence, the two air-blowing fans 13 arerotated by the driving motor 33.

Note that, in FIG. 6, the rotation shaft 32 secured to the left boss 31of the air-blowing fan 13 on the left is supported by a not-shownbearing.

In the above blowing device, the air-blowing fans 13 are connectedtogether by the joint 35. By simply changing the length of the joint 35,the longitudinal length of the blowing device can be easily adjusted.

Moreover, when the joint 35 is made of stainless instead of steel, theblowing device can be made lighter.

Third Embodiment

Described below is still another embodiment of the present invention,with reference to the drawings. Note that, for the sake of explanation,identical reference signs are used to denote components with identicalfunctions between the preceding embodiments and this embodiment. Suchcomponents will not be elaborated upon here.

FIG. 7 is a perspective view schematically illustrating the air-blowingfan 13 of a blowing device according to this embodiment.

In the air-blowing fan 13 as illustrated in FIG. 7, the disc face 13 bis inscribed with a marking 41 to distinguish between the left and theright of the disc face 13 b. An example in FIG. 7 shows that the sign “

” is inscribed as the marking 41 indicating left and the sign “

” is inscribed on the not-shown other side of the disc face 13 b as themarking 41 indicating right.

In this embodiment, the air-blowing fan 13 includes the two impellers 13a connected together through their respective disc faces 13 b. If theimpellers 13 a are mounted on the rotation shaft 32 in a wrongdirection, the air is blown in the opposite direction. That is, if theimpellers 13 a are mounted on the rotation shaft 32 in a wrongdirection, the impellers 13 a rotate in the opposite direction to theintended rotation direction. Hence, the air is not sucked in a faceperpendicular to the rotation direction of the impellers 13 a. On thecontrary, the air is blown out of the face. In order to avoid such aproblem, the marking 41 is inscribed on the disc face 13 b todistinguish between the right and the left. In this embodiment, a partof a mold for the impeller 13 a serves as an insert for inscribing themarking 41, so that the marking 41 is inscribed simultaneously when theimpeller 13 a is molded.

As described above, the marking 41 is inscribed on the disc face 13 b ofthe impeller 13 a. Thus, when mounting the air-blowing fan 13 on therotation shaft 32, a manufacturing worker can identify the left or thelight of the impeller 13 a by simply looking at the marking 41. Such afeature can reduce the risk that the manufacturing worker wouldinadvertently switch the right and the left when mounting the impeller13 a.

Moreover, the feature can reduce such a risk of inadvertently switchingthe right and the left in the mounting not only in the manufacturing butalso in re-assembling the impeller 13 a and the rotation shaft 32dismounted for repair and inspection after the manufacturing of theblowing device.

Hence, the feature makes it possible to clearly distinguish thedifference between the right and the left of the impeller 13 a when theimpeller 13 a is mounted on the rotation shaft 32 in manufacturing orrepair and inspection of the blowing device, compared with a case ofidentifying whether the right and the left are inadvertently switchedonce the rotation shaft 32 and driven. Thus, the feature saves thetrouble of mounting the impeller 13 a on the rotation shaft 32 againafter they have already been assembled together.

Note that, in the example illustrated in FIG. 7, the marking 41 isrepresented in, but is not limited to, Chinese characters “

” and “

” respectively equivalent to the left and the right in English words.Alternatively, English words “Right” and “Left” may be respectivelyinscribed on the right and the left of the disc face 13 b. Moreoverpairs “

(Right)” and “

(Left)” may be respectively inscribed on the right and the left of thedisc face 13 b.

Furthermore, depending on an assembly process, the impellers can bemounted not in the horizontal right-left direction but in the verticalup-down direction. Hence, the marking 41 may identify the verticaldirection.

That is, the marking 41 may be any given marking as long as the workerdoes not inadvertently switch the right and the left (up and down) whensecuring the impellers 13 a to the rotation shaft 32. Other than theabove inscription visually recognizable, the marking 41 may be embossed(not shown) on a portion of the disc face 13 b or the impeller 13 a, sothat the user can feel the embossed marking 41 to identify the right andthe left (up and down).

Furthermore, in the above example, two markings are inscribed or formedto identify the right and the left (up and down) of the two impellers 13a. Alternatively, the marking 41 may be inscribed or formed on at leastone of the two impellers 13 a because if the right and the left (up anddown) are identified for one of the impellers 13 a, the right and theleft (up and down) for the other impeller 13 a are also identified.

As can be seen, the marking 41 is provided to at least one of the twoimpellers 13 a to identify the direction in which the impellers 13 a aremounted on the rotation shaft 32. Such a feature makes it possible toreduce the risk of mounting the impellers 13 a on the rotation shaft 32in the wrong rotation direction.

Note that the marking 41 is formed using, but not limited to, an insertwith a mold for manufacturing the impellers 13 a. The marking 41 may beeither stamped or attached in the form of a sticker on the disc face 13b after the impellers 13 a are manufactured.

In addition, the two impellers 13 a of the air-blowing fan 13 are formedhorizontally symmetrically, contributing to component sharing. Such afeature makes it possible to reduce manufacturing costs.

SUMMARY

A sirocco fan according to a first aspect of the present inventionincludes the impeller 13 a including the boss 31 for securing therotation shaft 32 transmitting rotational force of a motor (the drivingmotor 33), the impeller 13 a rotating to suck air from a direction inparallel with the rotation shaft 32, and to eject the air from therotation face 13 d of the impeller 13 a, wherein the boss 31 is formedto protrude outward from the end face 13 c of the impeller 13 a suckingthe air, and is provided with the screw hole 31 a opening, on a sideface of a protruding portion of the boss 31, for fastening the rotationshaft 32 with a screw.

In the above configuration, the boss for securing the rotation shafttransmitting rotational force of the motor is formed to protrude outwardfrom the end face of the impeller sucking the air. The boss is providedwith the screw hole opening, on the side face of a protruding portion ofthe boss, for fastening the rotation shaft with a screw. Thanks to thefeatures, a blade of the impeller does not have to be partially notchedor removed in order to pass a screw through the screw hole, opening on aside face of the boss, when the rotation shaft is fastened with thescrew, unlike the case when the boss is formed inward in relation to theair-sucking end face of the impeller.

Such features make it possible to reduce a decrease in a volume of theair when a blade of the impeller is partially notched or removed.

In addition, a mold for forming the impeller does not have to be shapedinto a complex shape, unlike the case where a blade of the impeller isto be partially notched or removed.

In the sirocco fan, of a second aspect of the present invention,according to the first aspect, the impeller 13 a may include twoimpellers 13 a each having a face (the disc face 13 b) across from theend face 13 c sucking the air, and connected together through the face,and the screw hole 31 a opening on the boss 31 of one of the twoimpellers 13 a and the screw hole 31 a opening on the boss 31 of anotherone of the two impellers 13 a may be provided not in a single plane.

In the above configuration, when two impellers are connected together,the screws tightening the rotation shaft on the bosses for the twoimpellers are provided not in a single plane, thereby reducing animbalance of weight distribution due the weight of the screws. Such afeature contributes to stable rotation of the two impeller.

In the sirocco fan, of a third aspect of the present invention,according to the second aspect, the screw hole 31 a opening on the boss31 of one of the two impellers 13 a and the screw hole 31 a opening onthe boss 31 of the other one of the two impellers 13 a may shift 180°from each other in a rotation direction of the rotation shaft 32.

In the above configuration, the screw hole opening on the boss of one ofthe two impellers and the screw hole opening on the boss of the otherone of the two impellers shift 180° from each other in the rotationdirection of the rotation shaft. Accordingly, the screws tightening therotation shaft on the bosses for the two impellers are provided not in asingle plane, and are positioned to shift 180° from each other in therotation direction of the rotation shaft, thereby reducing an imbalanceof weight distribution due the weight of the screws. Such a featurecontributes to stable rotation of the two impeller.

In the sirocco fan, of a fourth aspect of the present invention,according to the second or third aspect, at least one of the twoimpellers 13 a may include the marking 41 identifying a direction inwhich the rotation shaft 32 is mounted.

When a typical sirocco fan rotates in a wrong direction, the air is notsucked in a face perpendicular to the rotation direction of theimpellers. On the contrary, the air is blown out of the face. In orderto avoid such a problem, the impellers need to be secured to therotation shaft not to rotate in the wrong direction.

As can be seen, the marking is provided to at least one of the impellersto identify the direction in which the impellers are mounted on therotation shaft. Such a feature makes it possible to reduce the risk ofmounting the impellers on the rotation shaft in the wrong rotationdirection.

In the sirocco fan, of a fifth aspect of the present invention,according to any one of the first to fourth aspects, the boss may bemade of aluminum.

In the above configuration, the bosses are made of aluminum,contributing to reducing the weight of the sirocco fan as a whole.

A blowing device of a sixth aspect of the present invention includes thesirocco fan (the air-blowing fan 13) according to any one of the secondto fifth aspects, the sirocco fan (the air-blowing fan 13) including aplurality of sirocco fans (the air-blowing fans 13) rotatably connectedtogether in series.

Such a configuration allows the blowing device to supply a sufficientvolume of air.

An air conditioner of a seventh aspect of the present invention includesthe sirocco fan (the air-blowing fan 13), according to any one of thefirst to fifth aspects, serving as a blowing device.

In the above configuration, the air to be obtained is larger in volumeand higher in pressure compared with a case of using a cross-flow fan asthe air-blowing fan. In the use of an HEPA filter for air purification,such a feature makes it possible to ensure a sufficient volume of theair (a sufficient volume of the air to be sucked).

The present invention shall not be limited to the embodiments describedabove, and can be modified in various manners within the scope ofclaims. The technical aspects disclosed in different embodiments are tobe appropriately combined together to implement an embodiment. Such anembodiment shall be included within the technical scope of the presentinvention. Moreover, the technical aspects disclosed in each embodimentare combined to achieve a new technical feature.

REFERENCE SIGNS LIST

-   13 Air-Blowing Fan (Sirocco Fan)-   13 a Impeller-   13 b Disc Face-   13 c End Face-   13 d Rotation Face-   31 Boss-   31 a Screw Hole-   32 Rotation Shaft-   33 Driving Motor (Motor)-   35 Joint-   41 Marking

1. A sirocco fan comprising an impeller including a boss for securing arotation shaft transmitting rotational force of a motor, the impellerbeing configured to rotate to suck air from a direction in parallel withthe rotation shaft, and to eject the air from a rotation face of theimpeller, wherein the boss is formed to protrude outward from an endface of the impeller sucking the air, and is provided with a screw holeopening, on a side face of a protruding portion of the boss, forfastening the rotation shaft with a screw.
 2. The sirocco fan accordingto claim 1, wherein the impeller includes two impellers each having aface across from the end face sucking the air, and connected togetherthrough the face, and the screw hole opening on the boss of one of thetwo impellers and the screw hole opening on the boss of an other one ofthe two impellers are provided not in a single plane.
 3. The sirocco fanaccording to claim 2, wherein the screw hole opening on the boss of oneof the two impellers and the screw hole opening on the boss of the otherone of the two impellers shift 180° from each other in a rotationdirection of the rotation shaft.
 4. The sirocco fan according to claim2, wherein at least one of the two impellers includes a markingidentifying a direction in which the rotation shaft is mounted.
 5. Thesirocco fan according to claim 1, wherein the boss is made of aluminum.6. A blowing device comprising the sirocco fan according to claim 2, thesirocco fan including a plurality of sirocco fans rotatably connectedtogether in series.
 7. An air conditioner comprising the sirocco fan,according to claim 1, serving as a blowing device.